Wasps

Dave Rushworth

Although every aspect of nature is fascinating, I have, like many others, been attracted to birds. However, if I had my time again and knowing what I do now, I would choose to study the world of wasps, which fill almost every conceivable niche within their realm. The 'wasps' belong to the order HYMENOPTERA which includes the Ants and Bees and sawflies.

The order contains about 198 000 species worldwide of which the southern African region has over 6 000 species. The term 'Hornet' is a European and American term for some species of the Family VESPIDAE. The 'Yellow Jacket or Vespula germanica is a species that has been introduced to the western Cape and which can form very large colonies.

One colony of this species in New Zealand measured over fourteen feet (over four metres) in diameter. In southern Africa the term 'Wasp' is generally used. Most wasps have a painful sting which they can withdraw and use again, unlike the familiar 'Honey bee' which dies as a result of leaving its sting and attachments in the victim. All are characterised by pairs of single wings and, apart from Sawflies, narrow 'waists'.

Bird world

The mention of New Zealand reminds me that this was a country where the native, terrestrial mega-fauna (apart from two species of specialised bats) consisted solely of birds. There were no mammals native to that country. Fourteen species of Moa comprised the country's largest animals. The tallest could stretch up to six metres, like our giraffe, and was the tallest bird recorded on earth. Bulkier species were like the Apeornis (Elephant Bird) of Madagascar and able to force paths through thick bush.

The largest eagles ever recorded occurred there - Haast's Eagle - Harpagornis moorei, and the Chatham Island Sea Eagle - Haliaeetus australie plus a Goshawk equal to the earth's largest, helped to keep the fragile ecosystem in balance, until humans arrived. All terrestrial macro-systems were kept operating solely with bird species.

Wasp world

As with birds, in the example above, it is quite feasible that 'Wasps', with their great diversity, could run micro-systems in their own little world. I will not try to define all the thousands of species of wasps as the information is available in books for those who are interested.

Briefly, I will describe some of the niches or activities of certain species in the hope that it will draw attention to and generate interest in this very diverse and economically valuable group of insects. Some of the smallest wasps are the 'fig wasps'. The fertilised females of these wasps enter these 'flower capsules' (that we call fruit) through the small, one way hole at the base of all 'figs'. Once inside they feed from and cross pollinate all the tiny florets (that many people call seeds) within the 'fig'.

They lay their eggs which hatch into winged females and flightless, worm-like males. After mating, there being no way out, the males bore exit holes in the flesh and skin of the fig through which the females escape for further work. The males die in the fig, having completed their task, and the successfully pollinated flowers form seeds, which are then dispersed by birds and other animals.

As a matter of interest, most fig 'seeds' have to encounter very high temperatures before they will germinate hence the occurrence of young figs on top of rocks, on dead tree trunks etc rather than in deep plant litter. There are many species of 'Spider Wasps' ranging from small to very large and normally a dark, metallic colour.

The largest species are capable of overpowering the biggest 'Baboon Spiders'. Most make a rattling buzz during flight, which seems to alert spiders to take a defensive stance. This attracts the wasps, which must have good eyesight. After a short manoeuvre the wasp gives the spider a paralysing sting and then carries or drags the immobile spider to a prepared hole, where it lays an egg on the spider before burying it. When the egg hatches the paralysed spider provides food for the wasp larva to develop into a new wasp.

Many species of wasp parasitise other insects (even among their own Order). Some have long 'tail-like' ovipositors through which they lay eggs on or within living individuals. The developing larvae then devour the doomed 'prey' which slowly perishes. Other wasps use their ovipositors to probe and lay eggs in timber and fruit. Certain wasp species construct intricate 'nests'.

The 'paper wasps' chew vegetation (even thatch on roofs) to form a 'mash' from which they construct the well known 'paper nests'. Other species gather mud to form the many different shapes of mud nests. The 'potter wasps' - Afreumenes aethiopicus - form delicate 'urns' attached to various surfaces. The 'leaf wasps' cut and curl up leaves.

Some just dig holes in the soil. In each case they form a compartment in which they lay an egg which hatches into a lava (grub). Some larvae are pre-fed, as mentioned, but others have to be fed by the adults. When fully formed the larva are then covered over to pupate into new adults. It is at this breeding stage that 'groups' of wasps can be very defensive and most likely to sting intruders. A good antidote to the stings is raw 'Dettol' dabbed on the site of the sting.

Wasp stings, although painful, are rarely as threatening as bee stings and have no long lasting effect. The metallic green 'cuckoo wasps' are very hard shelled and impervious to attack Although every from others. They drill holes into the mud nests of other species and lay their eggs on the existing larvae. They also steal food from the nests of other species. Another very hard-shelled species is the 'wingless wasp' or 'velvet ant' in which the female is wingless.

The male has wings enabling it to visit flowers for food. There is an almost unending list of predatory wasps and their prey species. There are 'mammoth wasps' that parasitise beetles, there are 'cockroach wasps', 'ant wasps', 'grub wasps' and so it goes on - each with their own interesting habits. There are also many nectar feeders which assist in the cross pollination of many flowers. Some plants rely solely on wasps for pollination. It is impossible, here, to describe every activity and prey species.

The point to remember is that all 'wasps' are useful creatures. The little damage that some may do to crops is minimal payment for the good they do in helping to control spiders and other insects, their own relatives and for helping with crop pollination. Treat them kindly and they won't sting you. They only become defensive when threatened.

Take time to notice the different, delicate shapes of various species, the direction finding ability, the nest building activities, the feeding methods and the infinite variety of fascinating nest constructions. You will be well rewarded.